Power transmission



.April 22, 1947. R. A. SHARTLE' y 2,419,374

POWER TRANSMISSION i Filed Oct. 30, 1941 l so d'- ATTORNEY |05 ROBERT A. SHARTLE I6 BY I i otherasauid motor.

?nientee POWER TBANSNIISSION netart A. Sherrie, Rsekrurd. ni., assigner Le 'Vickers Incorporated, Detroit, Mich., a. corpora-y tion otfii/lich'lgan niieatlon October 30,1941, Serial No. .417,087 iifClaims.'A (G60-552) This invention relates to power'transmissions, ever a predetermined pressure is exceeded in the particularlyto those of the type comprising two i. delivery conduit I8. or more iihuidv pressure energy translating devices', 'Y Conduit vIii extends to a pilot directional fourone of which may function as a pump and anv way valve 24 which comprisesa main body having n :5 a' longitudinalbore 26 which is provided with a. 'I'he"inventionis more particularly concerned 'pluralitylof ports arranged along its length, of withl a power transmission system for driving an @which 2811s a pressureport, 36 and 38 are cylinalternately reversing load device,V for example, der ports, and 30 and `32are `tank ports which the lmovableslide of amachine-tool such asa .-.co'nimunicatewith tanky I 6' through conduits 34 planer. or sharper.,v land/'particularly one 'having *510iy and i234, For Ycontrolling the communication bef considerabieinema. m systems applied io--tnis' tween thev veriousrports. thereis mounted in bore y class of service, 'it is-important', that the means `for stoppingA the slide atwill bejefi'ectivetobrake.- the momentum* promptly *.to v.prevent overtravellf.`

- bysomewhat complexlapparatus, and it-"is Y' an cbiectzof the` present;inventiontoprovidegby 3 l means of ssimplifledcircuitfdpower transmission f 2B aislidablefspool 10 which comprises arstem -'having..two' solid lands 42 and and a valve iplunger '45 whichextends-downward throughv an This result'jhas "been '.achi'e'vedi'in .previous ciry-V :151cm cap toa reciprocating mechanism 6U onto "for, the operation thereof. `Slide lll is moved by va rod 54 whichis attached to piston |52 mounted l system'otthe charactervdescribedwhich provides", "fin cylinder i132. The cross'section area 'of rod safe and positivestoppingwith a minimum off 2oy |54 is` preferably one-haii",the areal ofthe leftovertraveland withk considerable jsimpliflcationrifend 'oi'Distor'i-l'Z;`V l i v Y i i From ports as Vand :ser puoivaive 24 cene f It is also an object to' provide in a system oi!` y duits 58 and'58 extend to the rod and head'ends,

` this character an overload protective'valve whichv respectively, of an'automatic stroking cylinder 8U,

- is effective during the braking operatiqnandto ,so 25.- atta'ched tdpumpt hereinafter described. con-- arrange a. single auch valve in thek circuitthat taining a movable piston 62 having e rod 64 which Lit :s esecuve to brake the momentum of the slide 1 .remite Aa, yoke 88, thus regulating the volume of regardless of which direction lthe slide ig :rn-Whig` fiuldvow ofthe pump 90. Its minimum ow is A further object is'topr'ovidea system offthisf-f .ffdetermined byan adjusting screw ill which is f character wherein a singiereiiei. vaive acts not; 39 Set to a point above the neutral position to preonly asa pressure limiting device during braking vent short stroking the pump 90 to zerondisplace.

. but is also so located-inthe circuit as io anord'iments f v 1 .Y the normal supply. pressure limiting action durv i Conduit ivvhasbranch conduits 66 and S8, of v i 'e which 66 leads toa cylinder 10 which contains ingoperation. f

Further objects and advantages of the present 35511 Slidable piston 14, Spring returned. nd a rod invention will be apparent from the following de- 15 v'lifiched thereto Which meshes With 9 gear scripnon, reference beim;l had tothe accompany- 'I8 to lift tool 80 during the return stroke. while .t ing drawing wherein a preferred form of the pres- 68 leads tothe rod end of a cylinder 'l2 which ent inventionis clearly Shown l i comprises a ymovable piston 82and a rod 84 to In the drawing the singlevviigure is a. di ram- 40 matic view of afpower transmission systaegm in acr'sthswlorli Coldl ibas also a branch co man r I lcon t ea ng., o e rght end of valve rpo g a' p e erred form of thepresent in H0, While the left end of valve lill communicates vention. i

with conduit 584 through branch conduit 89. :here is indicated at a Suitable prime mover k45 Pump 9u, attached to the iefthand end of the auch as an electric motor, adapted to drive two mmm. m is a piston type liable delive um hydraulic pumps Simultaneously, One 0f which" provided with anautomatic stroke regutgr edl ttaohed t0 the righthand end 0l motor l0, iS hereinbefore described, which increases the vol- Small auxiliary constant displacement pump ume of flow during the return stroke and de I2- which supplies Pilot pressure for the circuit. 50 creases it during the feed stroke. Pump 90 has Pump l! withdraws iluid from a, tank i8 through a suction conduit 92 which has mounted therein a suction conduit I4 and delivers the same to a a check valve 4| for allowing liquid to be withdelivery conduit I8. The latter has a relief valve drawn from the tank I E. Suction conduit S2 also 20 of conventional construction for bypassing oil communicates through conduit 98 with a presto the tank I6 through conduits 22 and 23 when- 55 sure responsive vaive 95 which permits excess Lwhichare attachedv adjustable cams-52 and 54 operate the cross feed 85 which moves tool 8u v connecting ports and |06, thus bypassing to Y tank I6 whatever oil is required to cause presconduits I|2 and I|4 lead to a, manually oper-- ated start and stop valve I|'6. The latter comprises a. main body having a longitudinal bore I I8 vwhich is provided with annular ports arranged along its length, communication between which is controlled by a spool I|1 which comprises a stem having two lands ||9 and |2|. The left end of the spool ||1 has secured thereto an operating plunger |29 which is attached to a. manually operated lever |23. End caps |25 and |21 close both ends of the valve ||6, the former cap closely enveloping the plunger |29, forming a liquid tight nt.

Ports |20 and |22 of valve I|6 communicate with the inlet-conduit |08 through conduits ||2 and ||4, respectively, while port |24 is connected by a conduit 98 which leads to the suction side of pump 90. Port |26, a cylinder port, is connected by a conduit |30 which leads to the rod end of a cylinder |32, passing through a relief valve |34. The latter is of conventional construction for bypassing oil to tank I6 through conduit 23 whenever' a predetermined pressure is exceeded in conduit |30. Relief valve |34 also functions as a safety valve .during `.the braking period, hereinafter described, to relieve excess pressure caused by the inertia of the slide 50 when it is suddenlyv stopd.

Port |33 ofl valve BIB is connected by a conduit |38 which extends therefrom, bifurcates and enters valve H0 through ports |40 and |42. AValve H0 comprises a main body having a longitudinal bore |44 provided with annular ports arranged along its length, of which |46 is a. plugged port and E48 a cylinder port which communicates with the head end of the cylinder |32 through a conduit |50. The latter has an auxiliary conduit II leading to the head end of .the cross feed cylinder 12, hereinbeiore described. Communication' between the various ports is controlled by a hydraulically operated spool Il which comprises a stem having four lands M3, |451, |41 and |49.

thereon. l

Valve H8 is provided with end caps |60 and |62 which contain small metering valves to control the speed of sluiting of the valve spool |4|. The metering valves consist of ball check valves |68 and |10, held in place by light springs I1I and |13 and metering pins |64 and |66, respectively, which can be adjusted from zero to free flow. The oil enters the valve IIO through. a ball check valve onone side, and as oil leaves the other side it exerts pressure against the ball check valve closing that port, causing the oil to pass through the metering pin. By controlling the iiow of the exhausting oil from the valve ||0, the speed of the spool |4I is controlled thereby, eliminating the l d impact caused by the too rapid shift of the valve spool |4I.

In operation, while pumps 90 and |2 are being driven by the electric motor I0, oil is withdrawn from the tank |6 through suction conduits 92 and I4 and delivered to delivery conduits |08 and I8, respectively. Conduit |8 o pump I2 directs the fluid to the pilot valve 24, which, it may be assumed, is in the position shown. Since valve member |4| and stroking piston 62 are already moved to the end'of their respective strokes, no

fluid can escape through conduit S8, so the full pump delivery is bypassed to the tank I6 through relief valve 2|) and conduits 22 and 23. While conduit |08 of pump 90 directs the liquid to valve ||0, the' spool being-to the right connecting ports |01 and |46, no liquid can escape through this path, and liquidis caused to enter valve I|6 through conduit I| 2. Ports |20 and |24 being connected, thev liquid is directed to conduit 38 which communicates with the suction conduit 92, thus causing the liquid to circulate at no pressure.

Prior to beginning the operation, Withall parts in the position illustrated, pilot valve 24 connects pressure port 28 with cylinder port 38 and cylinder port 3,6 with tank port 30. When the lever |23 ofthe stop and start valve ||8 is shifted to the left to .start the operation, it connects port |36 with -port |24 and -pressure port |22 with cylinder port' |26.

` Pilot pressure in. conduit 58 is mairrtainedin v A stopped therein by the plugged port |46, and it enters valve ||6 through conduit ||4. Ports 22 and |26 being connected, the liquid is directed through conduit |30 to the rod end of cylinder |32, causing the piston |52 to move to the left. The discharging liquid from the head end of the cylinder |32 is exhausted through conduit |50, ports |48 and |40 of valve ||0, conduit |38, ports |36 and |24 'of valve IIB, and conduit 98, which leads to the suction side of the pump 90. As the pressure responsive valve 86 sets up a back pressure therein, the liquid is caused to flow through branch conduit |5I of conduct |50 to the head end of the feed cylinder 12, causing tool to be moved across the Work, setting it in a position to cut. The excess oil not required for prelling the pump 90 will be bypassed over the pressure responsive valve 96, as only one-half of the liquid returned from the head end of the cylinder |32 is delivered to the rod end thereof. A

Ii' the need of stopping the slide 50 arises during this feed cycle, lever |23 oi valve IIB is shifted to the stop position, illustrated, connecting port |20 with'port |24, directing the pump delivery to conduit 38, causing it to simply circulate, While port |36 connects with port |26, diverting the discharging flow from conduit |38 to conduit |30. As this oil amounts to approximately twice the amount of the oil that can. be accommodated in conduit |30, pressure will immediately build up in conduit |30 to a. high value limited by the setting of relief valve |34, causing the table 50 to promptly stop.

Whenthe slide 50 reaches the end of its cutting stroke, an adjustable cam 54 mounted thereon will shift the pilot valve 24 to the return position, connecting pressure port 28 with cylinder port with Hfandblockingmpo'rts |40 and-H2 rodend olf-"the strokingcylinderfliof lpurnpl'Sli;

shiftingthe'fyoke 88 to its maximumiposition; Simultaneously, the' pilot pressurerentersfbranch conduits 66 and 685 forcing back pistoniof/cyl inder 210, :lifting-tool i 801' outfofethef path fTof the work, and returning piston` 82.; o'f .cylinderr'fllto its start'f position; illustrated; respectivelya'f It also enters branch conduit 86, shiftingvalvef'spool |l`| i of: valve- I toy theV left, -co'nn'ectingi port-1| nl The pump delivery isfnowf: directedlfthrough conduit-"1 08, Sports-i101 and HB'of va-lv'ei I |0`i .an'd conduit |50 to the headend of the cylinder-|31".v Asvalve'll' is inirn position, that is, valve spool thereofu beingwtowtheleft connecting ports |22 and |26,'-the workingfpressure is directed also through; Conduit-i |4-to-: =ond.1.1i.t. i311; tothe rod end of the cylinder |32, forming a diierential action andv` causing the. piston |52 t o return to the starting position, that'i"s;to the right.

If theneed arises to stop the slide lifduring'. this'cycla'ilever |23 of valvelilis pushedinward `to thestoppostio'n, illustrated, connecting pori; with,port|24, again Adirecting thejpunip delivery to conduit.98, causing-'itto circulateat Y, no pressure,1while Aport,|26,-:conn'ects withfport |36, diverting the dischargingfiluid fronicon'duit |30 to conduit |38, entering valve ||0 at ports |40 and |42. The latter being blocked, spool |4| .being to the left, causes the slide-50 to immediately stop. Because of this sudden stop plus the inertia of the table 50, the excess pressure built y up in 'conduit |30 is bypassed over the relief valve |34. f When the slide 50 reaches the end of its return stroke, the cam 52 mounted thereon will shift the pilot valve `24,'provicling for a feed stroke, hereinbefore described, continuing the oscillation until the start and stop valve I6 is shifted to the stop position.

Thus it will be seen that the invention provides a. means of driving a reciprocating mecha.- nism, stopping the same promptlyin either direction, and utilizes a considerably simplified circuit incorporating a relief valve which limits the working pressure and also acts as a safety valve during the braking, operation, relieving excess pressure caused by the inertia of the slide.

While the form of embodiment of the invention as herein disclosed constitutes a. preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In a hydraulic power transmission for operating an alternately reversing load device, the combination with a source of pressure iiuid, a diii'erential iluid motor for operating the load device by fluid supplied from said source, a reverse valve for selectively directing iiuid to, or exhausting the large area of the motor, a runstop valve for selectively bypassing the source or blocking such bypass and concurrently respectively blocking or supplying iiuid from the source the reverse valve.;

draulically-braket theigniotor in either position of 'a 125,111A ashydrauli'c powerftransmission forloperatingv an c alternately; reversing r load device, ,the

. combinationfwithifasource ofE pressure uid, a

diiferentialiiuidf 'motors` for, operating.r i the. load device bygliluid.fsuppliedairomxsadfsource, a refverse -zvalve' forfselectivelyfdire ingffiluid $0,501' exhausting ,the large area .of the. motor, a runstopfvalve,V `r`for: selectively.;:bypassingl theg, source onblocking sucl'r bypass andconcurrentlyy respectivelyiblockingwonsupplyingaiiuid from thefsource to2 thr-.smallgarea or the motor including; a :connectionbeyond vrthey reverse,svalve;y `to iexhalLSt; the differentialv'olume fromthe large areaof the cylinder while the small..area:isbeingfsupplied.with iluicl; aii'dffazcircuitf.connecting thesource, motor and valveseixicludingia ,connectiom from the small are of theftmotor, and#throughefsaidrun-stop valvestci the' reversezgvalve and establishedzbythe runs-stop,v valve -in itszstonzposition l:togh'ydraulically bralreff-thef.motoriiny eitherfpositioni of the reverse valve, :said -fconnectionrfiincluding 1a pressureY responsive vrelieffivalve vfor-'limiting the maximum pressure. built npdnfsaid-connection bythe inertiavof the loaddevicelduringstopping.:` ,1 f

l; 3. .'Inz'a .hydraulicpcwen transmission for operatingfans alternately'f reversing load device,v the combination-'mitin a`l source ofc pressure iiuid,v a differential fluid motor for operating the load device by fluid supplied from said source, a reverse valve for selectively directing fluid to, or exhausting the large area of the motor, a run-stop valve for selectively controlling the supply of uid to the small area of said motor or stopping the same including a connection beyond the reverse valve to exhaust the differential volume from the large communication between the large and small areas to the small area of the motor including a connection beyond the reverse valve to exhaust the diiierential volume from the large area of the cylinder while the small area is being supplied with iluid, and a circuit connecting the source, motor and valves including a connection from the small area of the motor and through said runstop valve to the reverse valve and established by the run-stop valve in its stop position to hyof the motor.. v

4. In ahydraulic power transmission for operating an alternately reversing ioad device, the combination .with a source of pressure duid, a dierential uid motor for operating the load device by uid supplied from said source, a reverse valve for selectively. directing uid to, or exhausting the large area of the motor, a runvstop valve for selectively controlling the supply oi fluid to the small area of said motor or stopping the same including a connection beyond the reverse valve to exhaust the diierential volume vfrom the large area of the cylinder while the small area is being supplied with uid, a circuit connecting the source, motor and valves including a connection through said valves and establishing, when the run-stop valve is in stopping position and the reverse valve is in large arca exhausting position, communication between the large and smalll areas of the motor, and a relief valve in said circuit ecctive to limit the pressure built up by the inertia of the motor when such communication is suddenly established.

5. In a hydraulic power transmission for operating an alternately reversing load device, the combination with a source of pressure iiuid,4 a differential iluid motor for operating the load device by fluid supplied from said source, a reverse valve for selectively directing fluid to, or exhausting the large area of the motor, a runstop valve for selectively controlling the supply of uld to the small area of said motor or stop- I ping the same including a connection beyond the reverse valve to exhaust the diierential volume' from the large area. of the cylinder while the small area is being supplied with fluid, a circuit connecting the source, motor and valves including a connectionthrough said valves and establishingywhen the run-stop-valve is in stopping A dierential uid motor for operating the load de` vice by uid supplied from said source, a reversevalve for selectively directing fluid to, or exhausting the large area of the motor, a run-stop valve for selectively controlling the supply of fluid to the small area of said motor or stopping the same including a connection beyond the reverse valve to exhaust the differential volume from the large areaeof the cylinder while the small area is being supplied with fluid, a. circuit connecting the source, motor and valves including a connection through said valves and establishing, when the run-stop valve is in stopping position and the reverse valve is in largev area exhausting position, communication between the large and small areas of the motor, means associated with the Vreverse valve for blocking exit of uid from the small area through said connection when the reverse valve is in the position to direct fluid to the large area and the run-stop valve is in stopping position, and a relief valve in said connection eiective to limit the pressure built up in said connection when the run-stop valve is suddenly shifted while the motor is traveling in either direction.

ROBERT A. SHARTLE.

REFERENCES CITEDl l The following references are ci' record in the 

